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RFXANK gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

RFXANK gene

The RFXANK gene provides instructions for a protein that helps regulate immune system genes, and mutations in this gene are a primary cause of bare lymphocyte syndrome type II.

Normal Function

The RFXANK gene provides instructions for making a protein that helps control the activity (transcription) of major histocompatibility complex (MHC) class II genes. The RFXANK protein is a component of the regulatory factor X (RFX) complex, which attaches to specific regions of DNA to initiate the production of MHC class II proteins.

MHC class II proteins are found on the surface of immune cells, including lymphocytes. They are essential for the body's immune response, as they bind to peptides from foreign invaders (such as bacteria, viruses, and fungi) and present them to other immune cells. This interaction triggers the immune system to launch a defense. The RFX complex also plays a secondary role in the transcription of MHC class I genes.

Health Conditions Related to Genetic Changes

Bare lymphocyte syndrome type II

Mutations in the RFXANK gene are the most common genetic cause of bare lymphocyte syndrome type II (BLS II). More than 40 mutations have been identified in this gene.

  • Condition Overview: BLS II is a form of combined immunodeficiency (CID) characterized by a lack of immune protection, resulting in persistent and potentially life-threatening infections in the respiratory, gastrointestinal, and urinary tracts.
  • Mechanism: Mutations lead to an altered protein that does not function properly, impairing the ability of the RFX complex to bind to DNA.
  • Consequence: The failure to transcribe MHC class II proteins means lymphocytes lack these proteins on their surface, leaving the body unable to effectively recognize and fight off infections.

Frequently Asked Questions

RFXANK encodes a regulatory subunit that stabilizes the RFX complex on DNA. Mutations often lead to a truncated or misfolded protein that cannot bind DNA, resulting in a complete loss of MHC class II transcription. While RFX5 mutations also abolish MHC class II expression, RFXANK variants are more frequently associated with a broader spectrum of immunological defects, including impaired MHC class I transcription.
Families should ensure up-to-date vaccinations (excluding live vaccines unless the immune status is confirmed), use prophylactic antibiotics during high-risk periods, practice strict hand hygiene, avoid exposure to sick contacts, and consider regular monitoring of immune function to adjust IVIG dosing.===
Early detection relies on flow cytometry of cord blood to assess MHC class II surface expression. If abnormal, targeted sequencing of RFXANK is performed. Some centers also include RFXANK in panels for severe combined immunodeficiency (SCID) screening, allowing for earlier intervention.
Currently, no FDA-approved targeted therapies exist for RFXANK mutations. However, research is underway into gene editing approaches (e.g., CRISPR/Cas9) and viral vector–mediated gene replacement in preclinical models. Patients may consider enrolling in clinical trials focused on gene therapy for combined immunodeficiencies.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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